An overview of the latest OpenModelica functionality will be given, including the new backend, OMSimulator for FMI-based simulation and composition, Julia interoperability, CRML support and industrial applications of OpenModelica.

The convergence failure of iterative Newton solvers during the initialization of Modelica models is a serious show-stopper, particularly for inexperienced users. This paper presents the implementation in the OpenModelica tool of methods presented by two of the authors in a previous paper, to help diagnosing and resolving these convergence failure by providing ranked lists of potentially critical start attributes that might need to be fixed in order to successfully achieve convergence. The method also provides library developers with useful information about critical nonlinear equations, that could be replaced by equivalent, less nonlinear ones, or approximated by homotopy for more robust initialization.

Tasks involving Modelica models often do not simply investigate the dynamic behavior of a system, but rather want to characterize also possible optimal control strategies according to suitable criteria. Unfortunately, since Modelica does not support out-of-the-box optimization features, users are often forced to use other tools to code again the system model for optimization studies. For this reason, the authors present Modelica2Pyomo, an open-source tool to translate Modelica models into Pyomo optimization programs, leveraging on their flat Base Modelica representation. This work illustrates the main features of Modelica2Pyomo, including automatic variables and constraints normalization, expressions manipulation and initialization via Modelica simulation results. To demonstrate the capabilities of this framework, two examples are showcased, including an industrial relevant open-loop optimal control problem of a solid-oxide fuel cell.

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